Cover Crops and Types For Tropical Crop Farms

Cover crops (also written in single word, i.e., covercrops)
are plants grown or managed primarily to prevent the soil from being
eroded by wind and water. They are distinct from the ornamental groundcovers in landscaping which are primarily chosen for their aesthetic effects.

Covercrops can be either annual, biennial, or perennial plants. They
are grown as a sole crop or mixed. In addition to their usage for
erosion control, they help regulate soil temperature, suppress weed
growth, reduce pests and diseases, minimize loss of water from the
ground through evaporation, enhance soil fertility, add organic matter
to the soil, improve soil aeration, and promote high water
infiltration.

Several terms are used to describe various types of cover crops which are grown for special purposes.

Green Manures
are plants that are incorporated with the soil by plowing and other
means of cultivation while they are still green or soon after the
flowering stage, for the main purpose of soil improvement. Common
examples are the grain legumes cowpea (Vigna unguiculata) and mungbean (Vigna radiata)
after rice. Green manures are capable of adding organic matter to the
soil comparable to 9 to 13 tons per acre (22.24 to 32.12 tons per
hectare) of farm manure or 1.8 to 2.2 tons of dry matter per acre (4.45
to 5.44 tons per hectare) (Sullivan, 2003). Leguminous plants improve
soil fertility.

Catch Crops are cover crops
which are grown after harvest of a main crop to utilize residual
resources like soil moisture and fertilizers and to reduce nutrient
leaching. Both cowpea and mungbean become catch crops if they are
allowed to mature and harvested for pods. Other common catch crops after
rice are melons, garlic, tomato and many vegetables. These also include
those short maturing crops which are planted between two main crop
seasons.

Living Mulches are those grown and
maintained alive simultaneously with any cash crop, primarily to prevent
rapid loss of water from the soil through evaporation. Examples are
grass plants like Bermuda grass (Cynodon dactylon) and carabao grass (Paspalum conjugatum) under coconut (Cocos nucifera), oil palm (Elaeis guineensis) and in many orchards and vineyards. For rapid establishment of living mulches, leguminous vine plants are seeded.

Pasture and Forage Crop are those grown to be used as feed to livestock through pasturage,
soilage, silage or haying. These can be either grass alone, leguminous
crops, or mixed grass-legume crops. These crops are ideal in mixed
crop-livestock integrated farming system (
click to read how livestock integration benefited mango
). Common pasture crops in perennial crop farms integrated with ruminant animals are Bermuda grass, carabao grass, stargrass (Cynodon plectostachyus) and many leguminous vines.

Fast growing vines can easily cover the spaces between crop plants and kill weeds, including cogon (Imperata cylindrica),
by depriving them of sunlight. The shading of the soil will prevent
the germination of weed seeds. Leguminous plants are also good sources
of feed for ruminant animals. Being high in nitogen content, they are
excellent substitute to manure. Manure is mixed with carbonaceous
substrates in organic fertilizer production through vermicomposting or
with the use of Trichoderma as compost fungus activator (CFA).

Legumes are capable of fixing nitrogen from the air through a symbiotic association, called mutualism, with Rhizobium
bacteria. The amount of nitrogen that leguminous cover crops accumulate
range between 40 to 200 lbs per acre (44.83 to 224.17 kg per hectare).
About 40 to 60 percent of this nitrogen will become available to a
following crop if the cover crop is used as a green manure (Sullivan,
2003).

Common examples of tropical, leguminous cover crops are pinto peanut or creeping peanut (Arachis pintoi), calopo (Calopogonium muconoides), centro (Centrosema pubescens), kudzu (Pueraria phaseoloides), siratro (Macroptilium atropurpureum) and stylo (Stylosanthes guianensis).
All are perennial plants and, with the exception of pinto peanut,
vines. Seeds of these vine plants can be broadcasted or sown in furrows
at the rate of 15-20 kg per hectare.

The pinto peanut is also
popular as an ornamental crop. It is commonly used as a groundcover in
landscaping. It has stolons which produce roots and shoots at the nodes
and can be easily propagated from stem cuttings. A close relative, the
rhizoma perennial peanut (Arachis glabrata), is popular in
the US. As of 2008, more than 26,000 acres (10,522 ha) have been planted
to the ‘Florigraze’ and ‘Arbrook’ cultivars of the rhizoma peanut in
Florida, Georgia and Alabama. These were sold mostly for hay at prices
comparable to alfalfa (NRCS, 2008).